Beyond Shingo: Prompt, Do, Check, Act (PDCA) & Universal Mistake Prevention and Quality

Verification (UMPQV)

New tools for your "Lean" toolbox

Tom Wiesen

VP Engineering & Product Development - AVOW, LLC

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Agenda

• Introduction to PDCA• Poke-Yoke & UMPQV• Relationship between PDCA & UMPQV

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What is PDCA?

• Prompt, Do, Check, Act• Based on Shewhart Model (Plan, Do,

Study, Act) for continuous improvement• Model for any manual process

Operation Post Operation

Prompt Do Check Act

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“Prompt” Explained

• What does a Prompt do?– Initiate action– Authorize– Indicate

• What actions need to be performed• How the action is to be performed• Parameters of the action• What constitutes completion of the action

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“Prompt” Explained

• A Prompt encourages humans to perform the required process steps correctly.

• PROACTIVE prompts are much more effective than passive prompts

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“Prompt” Examples

Passive Proactive• Paper Manuals• Printed Instructions• Files that musts be

opened manually• Training (Memory)

• Buzzers• Lights• Voice• Electronic

displays

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“Do” Explained

• Perform (Control) the task– Methods

• Automatic (PLC, PC, etc)– Inputs: sensors, electronic data, software– Outputs: actuators, data, alarms

• Manual (Human Brain)– Inputs: touch, see, smell, hear, taste– Outputs: muscles, speech

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“Do” Examples

• Picking parts from storage locations• Placing parts in machines• Assembling parts• Operating hand tools (hammer, drill,

screwdriver, etc.)• Mixing solutions• Medical examinations/procedures

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“Check” Explained

• Verify that the “Do” was done right– Operation completed– Quality metrics– Quantity – Functionality

• Automatic checks are much more effective than manual checks

• Check should be objective

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“Check” Explained

• Types of Checks– Judgment– Informative

• Source Inspection• Self Check• Successive Check

– “Inspection” is controversial (non-value added)

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“Check” Explained

• Inspections should strive to be:– Frequent (100%)

• Occurrences of mistakes in human controlled processes are inherently unstable, making sampling operations useless

– Inexpensive– Simple

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“Check” Examples

• Visual inspection• “Feel”• Sound• Measurement (distance, torque, etc.)• Test equipment (pressure/leak test, etc)• Functional test

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“Act” Explained

• Act - Negative Outcome– Communicate outcome to:

• Operator• Control system• Quality/Production/Enterprise system

– Resolve negative outcome• Fix/Re-work/Scrap part• Find root cause• Correct cause

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“Act” Explained

• Act - Positive Outcome– Communicate outcome to:

• Operator• Control system• Quality/Production/Enterprise system

– Identify part– Transfer part

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“Act” Examples

• Indicating light or display• Transfer part to next station• Engrave serial number• Communicate results electronically• Repair defect• Remove part from line for disposition

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Part of a Lean Strategy

• What methods makes up Lean?– 5S– Kanban– Kaizen– Mistake Prevention (Poka-Yoke)– Total Productive Maintenance– Value Stream mapping– Takt Time– Cellular Manufacturing

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Part of a Lean Strategy

• How does PDCA fit into Lean?– Prompting

• Reduces wasted production time through increased productivity

• Reduces mistakes

– Check• Reduces Re-work & Scrap• Informative Inspection promotes Kaizen

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Part of a Lean Strategy

• How does PDCA fit into Lean?– Act

• Reduces time, money, and effort through communication with other systems

– Supply chain– Production systems– Quality systems

• Visibility of the entire enterprise allows what was previously seen as waste to be seen as added value

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Applying PDCA

• Use as design criteria for design of new manual processes

• Incorporate into Process FMEA– Instead of just looking at ways the process

can fail, look for absence of PDCA steps that ensure that process is correct

• Use to evaluate/improve current manual processes

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Overview of Poke-Yoke

• Japanese for “Mistake proof”• Developed by Shigeo Shingo• Primarily focused on preventing

mistakes before they become defects• Poke Yoke devices help prevent errors

and defects• Product Focused devices• Based on 100% inspection (Informative)

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Overview of Poke-Yoke

• Generally applied to discrete systems or processes

• Best applied to high volume, low variety production

• Generally not well applied to high variety production or complex operations

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UMPQV vs. Poka-Yoke

Universal Mistake Prevention and Quality Verification

• Includes all the elements of Poke-Yoke• Universal

– Process Oriented, not product oriented– Inexpensive, Redeployable, COTS

• “Mistake-Proof” split into Mistake Prevention and Quality Verification

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UMPQV - Universal

• Process oriented, not product oriented – Configurable to multiple product

applications• Easy to Integrate

– Standard physical and electronic interfaces– Programmable (Configurable)

• Expandable & Easy to change• Communication

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UMPQV - Mistake Prevention

• Essence of Poke-Yoke– Prevent mistakes before they happen

• Source Inspection• Self Check• Subsequent Check

– Based on 100% informative inspection

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UMPQV - Quality Verification

• Verify that the outcome is “Good” not just “Not Bad”

• Mistake Prevention is a precursor• “Mistake-Proof” does not imply that

quality is verified• Informative - If quality is not verified,

find out why and correct

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UMPQV - Examples

• DC Torque Tools– Socket Tray Indicates socket and proper torque

program (Prompt, Mistake Prevention)– Operator presses trigger, Controller Controls (Do)– Transducer/Current sensor verifies torque (Check,

Quality Verification)– Controller displays & communicates result (Act)– Tool is process oriented (torquing), product

independent, and provides communication (Universal)

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UMPQV - Examples

• Sensor-based Pick-to-light– Prompt light indicates bin (Prompt, Mistake

prevention)– Worker picks parts (Do)– Sensor detects proper pick (Check, Quality

Verification)– Controller communicates result (Act)– Tool is process oriented (part picking), product

independent, and provides communication (Universal)

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UMPQV – Poke-Yoke Conversion

• UMPQV devices do not have to be COTS– Go/No-Go gage used to verify/modify several

critical dimensions– Started with a few product variations– New Poke-Yoke devices (Custom designed

reference fixtures) were created for each product variation

– Over time, more than 30 custom devices created at significant expense and are complicated to use

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UMPQV – Poke-Yoke Conversion

• Poka-Yoke Issues– No method to ensure correct gage is used– No method to ensure any gage is used– Operator dependent results (subjective) – No communication or requirement for correction of

negative results

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UMPQV – New UMPQV Solution

• Electronic Measuring Device– Custom tool developed to measure critical

dimensions– Device has highly repeatable results– Communicates results to operator and

electronically to other systems– Setup/measurement requirements selected by

product model (Barcode or RFID)– Applicable to all product variations– Can require defect resolution (tagging, electronic

acknowledge, etc.)

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Example Comparison

– Array of Physical gages – No method for selecting

proper gage– No method to ensure that

any gage was used– High level of variation in

results– No communication– No requirement for defect

resolution

– One electronic measuring device– Barcode/RFID selects proper

program (Prompt, Mistake prevention)

– High repeatability and objectivity in results (Check, Quality Verification)

– Communication to Operator and electronically (Act, Universal)

– Lower life cycle cost of device

Poke-Yoke UMPQV

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Poke-Yoke vs. UMPQV

– 100% inspection – Poke-Yoke principles– Simple, Fast, Cheap

– Product specific– Low level communication– Best applied to high

volume, low variety production

– 100% inspection – Poke-Yoke principles+– Simple, but more complex

and higher initial cost– Process specific– High level communication– Best applied to high variety,

complex production

Poke-Yoke Device UMPQV Device

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Mistake Prevention Strategy

• Design mistakes out of product/process• Analyze process using PDCA Manual Process Model• Where mistakes can occur, use Source Inspection to

prevent occurrence of mistakes that lead to defects• Use Self and Subsequent inspections to detect

defects (100%)• Use Control methods over warning methods when

feasible• Use UMPQV solutions where there are common

processes and/or high variety• Use end-of-line testing as a last resort

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Questions?

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Pick-to-Light examples

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Torque Tool Examples

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SPC Example

SPC Error Catching

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Samples

Inspected Samples

Actual Defects